Touch sensitive displays are a well-known solution for user interfaces. The display senses the position of a touch on the screen. Additional features may be utilized in the user interface, when the display detects the force of the touch—for example the user may apply more force against the display to increase a displayed value on the screen. Different portions of the display may provide different force information to equal forces. A display having both touch and force sensing features may require calibration during the initial startup or periodically during the use of the device. The embodiments described below are not limited to implementations which solve any or all of the disadvantages of known displays with force sensors.